Toss the asparagus, mushrooms, red pepper, and cherry tomatoes with some olive oil, crushed garlic and salt and pepper - arrange on a baking sheet and roast in the oven at 400 F for about 20 minutes(just until there is some caramelization on the veggies). Set aside.
Cook the pasta according to directions - drain, rinse and cool.
Heat a large sauté pan on medium high heat with 2 Tbsp. olive oil - cook the prawns for about 2 minutes on each side - squeeze some lemon juice on at the end to deglaze the pan. Set aside.
For the dressing - combine the balsamic vinegar, olive oil, juice and rind of lemon, garlic, sugar, salt and pepper into a jar - put the lid on and shake really well. Add more sugar and/or salt and pepper to taste.
In a large salad bowl combine the spinach, roasted veggies, fresh herbs, olives, cheeses, pasta, prosciutto and prawns (with the juices from the pan).
Toss with the dressing to taste.